Just a side note:
The slots for machine racks are designed to handle an acceptable board thickness. For example, boards designed at .062 +/-10% still must accommodate the maximum thickness acceptable, which is over .068 (I think the slots are actually around .080)

Anyway, a .7% warp would be insignificant, unnoticeable.

Maybe they just used the .7% from the spec because "it sounds good" or else they are worried about something else (like a bad design). Whatever it is, it is almost certainly not the racks.

Maybe you should ask them what the REAL issue is...

Good Luck,
Jack

                -----Original Message-----
                From:   Shirley Xiao [mailto:[log in to unmask]] <mailto:[mailto:[log in to unmask]]>
                Sent:   Tuesday, May 09, 2000 10:16 PM
                Subject:        Circuit board material for SMT board

                 We use standard FR-4 laminate (Tg=130 C) to produce
                1.6 mm thick double sided PCB for a telecom-switch-box
                customer (laminate construction is 8X7628 with H/H
                copper foil) . My customer require warpage less than
                0.7% after reflow and wave soldering because the cards
                need to be inserted into slots of machine racks. They
                are looking for warpage less than 0.5% in three
                months.

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